Brake mechanism



SePt- 7, 19.43. R; H. cAsLl-:R 2,329,155

BRAKE MECHANISM Filed July 7., 1941- A 'f l l? l/ f e 31 3 wem/ko@ Pogr H. Casier.

Patented Sept. 7, 1943 BRAKE MECHANISM Roger Il. Casler, Elyria, Ohio, asslgnor to Bendix-Westinghouse Automotive Alr Brake Colnpany, Elyria, Ohio, a corporation of Delaware Application July 7, 1941, Serial No. 401,386

13 Claims.

'I'his invention relates to control mechanisms and more particularly to a valve mechanism of the so-called self-lapping type for the control of lluld pressure. f

It has heretofore been proposed to employ lluid pressure control valve mechanisms having intake and exhaust valves arranged to control the flow of fluid pressure from a source of nuid pressure to an actuator and to control the flow gf fluid pressure from the actuator to atmosphere, the operation of these valves being controlled jointly by a member responsive to the pressure in the actuator and by a resilient element such as a spring adapted to be compressed by means of a suitable leverage arrangement to oppose the action of the pressure responsive member in such a manner that the pressure in the actuator is always proportional to the degree of compression of the spring, which is commonly known as a graduating spring. In view of the fact that such springs have been serially connected between the operating lever and the valve operating member which is responsive to the pressure in the actuator, heavy springs have been required for this purpose and a large amount of force is necessary to actuate valves of this type when a high pressure is present in the actuator, with the result that the force which must be exerted on the operators pedal to obtain this pressure is often excessive, making satisfactory control of the brakes by the operator dilcult.

Valves of the above type are commonly known as self-lapping valves, it being well known in the art that with valves of this type, a condition of balance is reached at any desired pressure, determined by the degree of compression of the graduating spring, wherein the intake and exhaust valves are both in closed position and the pressure responsive member always returns to a pre-determined position under these conditions. Due to the necessity for employing relatively heavy graduating springs having a high rate of pick-up however, there has been a tendency for the rate of ilow of fluid pressure delivered by such valves to gradually fall off as the self-lapping point is reached, due to the gradual closing of the valves, which action has been detrimental in that it appreciably lengthens the time necessary to supply a given pressure to the fluid actuator.

The present invention, however, contemplates a novel arrangement of a resilient means or spring for actuating the valve mechanism in place of the serially connected graduating spring arrangement now commonly used in order to minimize the difficulties encountered with such valves in supplying a desired degree of lluid pressure to a fluid actuator in a minimum period of time.

A further object of the invention is to provide, in a mechanism of this general type, means for controlling the pressure delivered by the valve in such manner as to require a minimum amount of effort on the part of the operator.

Another object of the invention is to provide pressure responsive means under the control of the operator for actuating the valve mechanism, so constituted as to minimize the falling on in the rate of pressure delivery which is characteristic of valves wherein an operator controlled graduating spring is used to actuate the valve mechanism.

These and other objects and novel features of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawing. It ls to be `expressly understood, however, that the drawing is employed for purposes of illustration only, and is not designed as a denltion of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawing, wherein similar reference characters refer to similar parts throughout the several views:

Fig. 1 is a diagrammatic view partially in section, of a fluid pressure control valve mechanlsm for a fluid pressurel system constructed in accordance with the principles of the present invention, and

Fig. 2 is a diagrammatic view partially in section, of another embodiment of the invention.

Referring more particularly to Fig. l, the invention is disclosed therein as embodying a selflapping valvular mechanism having the left hand portion thereof constructed substantially in accordance with the principles disclosed in the patent to William J. Andres and Roy S. Sanford, No. 2,133,275, issued October 18, 1938. The valve mechanism includes a casing 5 formed of upper and lower sections 6 and 1 respectively, it being understood that the casing may be supported on the motor vehicle for convenient control by the vehicle operator in any suitable manner, not shown. The casing lis divided into a plurality of chambers, a partition 8 being provided and forming with said casing an outlet chamber 9 and an exhaust chamber I0. The lower casing member I is formed with a partition Il adapted to define, in connection with the casing and a cover member i2 suitably secured to the lower end of the casing, an intake chamber I3, the partition Il being provided'with a port I4 for connecting the outlet chamber 9 with the inlet chamber I3.,

Valve means are provided for controlling the ilow of iluid pressure from the intake chamber I3 to the outlet chamber 9, and from the latter to the exhaust chamber I8, and as illustrated, such meansare constituted by exhaust and intake valves I5 and I6 respectively, said valves preferably being oi! spherical form and rigidly connected as by means of a rod I1. A single spring I8 is interposedbetween the exhaust valve I5 and the upper face of the partition II in such a manner as to normally maintain the exhaust and intake valve'assembly in the position shown, wherein the intake valve I6 rests against the lower end of the bore I4, thus eiectively preventing the ilow of iiuidpressure from the inlet chamber I3 to the outlet chamber 9.

In order to actuate the valves I5 and I6 for controlling the iiow of fluid pressure to the outlet chamber` and also for controlling the communication between the outlet chamber and the exhaust chamber, a valve actuating member I 9 is utilized which is provided with an axial bore forming an exhaust passage. Suitably secured to the valve plunger I9 is a pressure responsive element 2| constituted by a diaphragm clamped as shown between the upper and lower housing portions 6 and 1, and acting in connection with the casing and the partition 9 to define a diaphragm chamber 22 and subjected to the pressure in the outlet chamber 9 through a choked p' sage 23 formed in the partition 8. A bore 24' is,i also formed in a portion of the partition 8 lconcentric with the plunger I9 and a sealing ring 25 is suitably mounted in said bore for guiding the lower end of the plunger and for preventing the :dow of :duid

. pressure between the chambers 9 and 22 except through the passage 23. The lower end of the bore 20 in the plunger I9 is normally maintained in spaced relationship with the upper surface of the ball valve I5 by means of a spring 26 interposed between a shoulder portion 21 of thev plunger and the upper face oi the partition 3. In order that the outlet chamber 9 may be normally connected to atmospherethrough the bore 29, the upper end of the plunger is provided with ports 28 adapted to establish communication between the bore 20 and the exhaust chamber I0,

which chamber in'turn communicates with atmosphere through an exhaust port 29 formed in the wall of the casing member 6. It will thus be seen that the portion of the valve mechanism hereinbefore described is substantially similar to that disclosed in the patent to William J. Andres and Roy S. Sanford, above referred to, and in order that this portion of the valve mechanism may be rendered effective for controlling the iiow of uid pressure in a system, the inlet chamber I3 is provided with an inlet port 30 connected with a pressure supply reservoir 3l as by means of a conduit 32, vwhile the outlet chamber 9 is connected with a uid pressure actuator 33 of any desired type by means of a port 34 and a conduit 35, it being pointed out that with the construction shown, the valves I5 and I6 may be sequentially operated on movement of the plunger I9 to supply fluid pressure from the reservoir 3| to the actuator 33, to maintain iiuid pressure in the actuator while disestablishing the connection therebetween and the reservoir 3I, or to connect the actuator with atmosphere for the purpose of exhausting uid pressure therefrom.

Operation of the valve actuating plunger I9 is an operating element 31 slidably mounted in a bore 38 formed in the right portion of the casing 4 and a compressed spring 39 interposed between the element and the lower end of the bore 38. An operative connection is established between the motor element 31 and the valve plunger I9 by means of a lever 49 mounted in pivotal engagement with the upper end of the element 31 as shown and having its other end in engagement with the upper end of the plunger I9, lateral movement of the lever 40 with respect thereto being prevented by means of suitable guides 4I on the upper end of the plunger, and upward movement of the left end of the lever 40 being limited by means of a stop 42 provided thereon and adapted to engage a portion of the casing member 6. The spring 39 is normally maintained in a precompressed condition through the medium of a movable fulcrum member 43 comprising an operating rod 44 slidably mounted in a bore 45 formed in the upper portion of the casing member 6 and retained in position by means of a cover member 46 suitably attached thereto, the right end of the operating member 43 being provided with rollers 41 and 48 separately pivotally mounted thereon as shown. the upper roller being adapted to travel on a track portion 49 formed on the lower face' of the cover member 46 and the lower roller 48 being adaptd to roll along the upper surface of the lever 40 on corresponding movement of the rod 44. It will thus be evident that with the parts in the position shown, the right end of the rod 44 is supported against upward movement by engagement of the roller 41 with the track 49, while the spring 39 is maintained in a compressed condition due to the position of the roller 48 substantially in alignment with the pivotal connection between the motor element 31 and the lever 49: It will also be understood that when the center of the roller 48 is in alignment withthe center of the motor element 31 there will be no tendency for the force exerted by the spring 39 to cause rotation of the lever 40 vabout the fuicrum roller 4s. n; win be seen from the foregoing description that the fulcrum roller 48 may be moved along the lever 40 to any desired position by the operation of the rod 44 through any suitable operator controlled means, not

shown, such as a mechanical connection between n an operating lever convenient to the vehicle operator and an eye 58 formed at the left end of the operating rod.

In operation and considering the parts to be so adjusted that the intake valve I6 is closed and the lower end of the bore 20 ofthe plunger I9 is slightly spaced from the upper surface of the exhaust valve I5, movement of the rod 44 and the attached rollers 41 and 48 to the left will establish a fulcrum point at some position along the upper surface of the lever 40, thus causing the force exerted by the spring 39 through the element 31 to rotate the lever 40 thereabout in a counter-clockwise direction, with a consequent tendency to move the valve operating plunger I9 downward, iirst closing the exhaust valve and subsequently opening the intake valve to admit iiuid pressure from the reservoir to the actuator 33 through conduit 32, port 30, intake chamber I3, open intake valve I4, outlet chamber 9, outlet port 34 and conduit 35. On opening of the intake Valve in this manner tof supply iiuid pressure from the reservoir 3| to the actuator, it is evident that the pressure of the uid in the outlet chamber 9 and in the actuator will subsequently be transmitted to the accomplished by means of a motor 36 comprising 75 diaphragm chamber 22 by way of the restricted 'tuating the valveoperating lever 40.

passage 23, with a resultant upward force being exerted on the diaphragm 2l and through the.

plunger I 3 to overcome the downward force exerted thereon through the lever 40, causing clockwise rotation of the lever 40 about its point ofA engagement with the fulcrum roller 48 rby an amount sufcient to cause compression of the spring 39 to yield a forcel acting through the lever 40 suiicient to balance the upward force exerted on the plunger I9 by the action of uid pressure on the diaphragm 2|. lThis action re` sults in closing of the intake valve Iii-thus cutting olf a further supply of pressure to the outlet chamber 9 and permitting the pa to reach a state of equilibrium in a lmanner w ll known in connection with self-lapping control valves of this general type. v

It is further noted that with the valves in lappedk position, the mechanism is so arranged as" sition with relation to the lever 40 is that-required to overcome the friction of the rod and of the rollers, the resultbeing that with the valve in lapped position, a new position of the rod-.44 can be selected for the establishment of a different pressure of either greater or lesser degree with the use of verylittle forceon the rod itself.

It will also be noted that withV the present construction the distance through which the graduating spring must be compressed or decompressed to cause corresponding actuation of the plunger I Sio loperate the valves is determined by the position of the fulcrum roller 48 in relation to thelever 40 and to the travel of the plunger'` I9 necessary to actuate the valves. Since the spring motor acts onthevalve plunger I9 with a largemechanical advantage whenI the fulcrum roller 48 is moved to the `extreme left, the force exertedA by the spring to obtain maximum delivery pressure corresponding to this pocause very little compression of the iiuid presl sition can be comparatively small and the `spring l may be-chosen so as to-have karate of pick-up tem and permit lapping of the valves is comparatively small, so that the intake valve tends to remain open to its fullest extent until a pressure is reached in the diaphragm chamber 22 which is nearly suilcient to cause lapping of the valve mechanism.

It may be desirable under .some 'circumstances to further decreaseY the pick-up rate of the motor which serves to actuate the valves, andI with particular reference to Fig. 2 of the drawing, novel means are provided in a similar valve stru-c-v ture for accomplishing this desirable end. The left hand portion of the casing is provided with way of a port 5|.'the motor element 31 being provided at its lower end with a sealing cup 52 for preventing the escape of uid pressure past the motor element 31 and into the upper portion of the casing. A stop 53 normally spaced from an extension 54 formed on the lower portion of the element 31 may limit downward movement of the element and the upper end of the element is in pivotal engagement with the lower side of the valve operating lever;40. A slightly different construction is used on the member 43, the right end o1' the member having a shoe portion 55 formed on its upper surface adapted to slide on the track 49 formed on ,the upper cover, a fulcrum portion 56 being adapted to move along the upper surface of the lever 40 in order to es- K tablish the fulcrum point for the lever vat any desired position between the two. extremes of movement thereof.

It will thusbe apparent that with the reservoir charged with fluidpressur'e an upward force will be exerted on the .motor element 31 due to the action of, fluid pressurethereon which will be substantially constant at all times,` andthat movement of the rod 44 and the ulcrum 56 to the left will cause the motor to impart a counu ter-clockwise rotation tothe lever 40 about the viulcrum point 56 for actuating the valve operating plunger I9 and supplying iiuidlpressure to the actuator 33 in the manner heretofore described. As the pressure builds` upin the fluid actuator vand in the diaphragm chamber. 22, it, will be evident that the vupward force acting on' theplunger I9 will tend to move it upward to lap the valves and impart clockwise-rotation to jected'at all times directly to the pressure in the. reservoir `3|, and due to the relatively large volunie of the reservoir, it will be apparent that downward movement of the elementv 31 will sure acting thereon, and that consequently the T. pick-up which is characteristic of a. springused in this position will vbe;substantially absent and the intake valve will tend to remain open-fully until the force'acting upward on-the diaphragm 2I due to the pressure inthe chamber 22 is Sullicient to overbalance' the force exerted on the lever 4i) by the motor element 31 in response to the pressure supplied thereto from thev reservoir valve mechanism, including exhaust and intake valves I5 and I6, a valve. operating plungerIB and a pressure responsive diaphragm 2|- in a manner substantially similar to that shown in Fig. 1 of the drawing, the only important dif- 3I. the valves is of the piston type, it will be understood that a diaphragm or' other equivalent structure can be able. f v v n While two embodiments of the invention have been illustrated and described herein with conused if lthis proves to bedesirsiderable particularity, iit is toy be understood' that the same'are not limited tothe form shown "l but may receive a Variety ofu mechanical ex-y pressions as will readily appear'to those skilled in the art. Reference will, therefore, be had to the appended claims for a definition ofthe limits of the invention.'-

ference being in the construction of the motor mounted inthe right end of the casing for'ac- In the particular embodiment shown in Fig. 2, the bore 38 formed in 'the right portion of the casing 36 is provided with a motor element 31 slidably mounted therein land acted on by iiuid pressure supplied thereto from the inlet chamber I3 by What is claimed is:

1. The combination in a fluid pressure control valve having a casing provided Withfintake and exhaust valves and a` pressureresponsive member for controlling vthe operationbf the valves, of a motor of a type producing a substantially constant'force for actuating said member, a lever connecting said motor and member, and a movable fulcrum associated with said lever and mov- While the uid motor shown vfor operating 2. Thecombinationinasiluidpressure conltrol valve having a casing provided' vwith vintake and Vexhaust valves and apressure responsive member for controlling; the operation ffthe valves, 'of a motor of a typeexerting a substantially constant force having an element movable V, for operating said member. an operating lever iorsaid member having a pivotal connection therewith and a pivotal connection with said mo- "tor elementat a point spaced therefrom, and a valves, ofmeans for'actuatingsaid'mernberfing Vcluding a motor o! a typeeproducingasubstantially constant .force, leverage..mechanism for connecting said motor andlmember,`.and means movable with respect. tosa'jidfmechanism for varying the Vmechanical advantage'of said leverage mechanism.

3. The combination in a uid pressure control valve havinga casing provided with intake and exhaust valves and. a pressure responsive member for controlling the operation of the valves, of means for actuating said member including` a pre-compressed spring, a lever having a portion in operative engagement with said spring and another portion in operative enmovable tulcrum associated with said casing and f lever andl movable between said pivotal points trol valve having a casing provided with intake I gagement with said member, and a fulcrum mov- 4. The combination with a fluid pressure con-v trol system including a source of iluid pressure, a iluid pressure actuator, valvular means for controlling the ilow of iiuid pressure from said source to said actuator, and a member responsive to the pressure insaid actuator for controlling the operation of said valvular means, of a uid motor actuatedby the pressure from said source, means for effecting an operative connection between said motor and member, and means cooperating therewith and movable with respect thereto for varying the force applied to said member by the operation of said motor.

5. The combination in a fluid pressure control system including the source of iluid pressure, a iluid actuator, and valvular means for4 controlling the ilow of` fluid pressure from said source to said actuator, of means responsive to the pressure in said actuator for controlling the operation of the valvular means in one direction, means responsive to the pressure at said source for controlling the operation of the valvular means in the opposite direction, and means including a movable fulcrum for effecting an operative connection between said pressure responsive means for controlling the pressure delivered-to said actuator from said source 6. The combination in a fluid pressure control system including a source of uid pressure, a iluidl actuator, and valvular means for controlling the ow of iluid pressure from said source to said actuator and from said actuator to atmosphere, of means responsive to the pressure in said actuator for controlling the operation of said valvuar means in one direction, means responsive to the pressure at said source for conv -trolling the operation oi' said valvular meansin the opposite direction, means for effecting an operative connection between said rst and sec- -ond pressure responsive means, and means including a movable fulcrum cooperating therewith for rendering said second named pressure responsive means effective or ineiective to control the operation of said valvular means.

v'7. The-.combination in a iluid pressure control valve having a casing provided with intake and exhaust valves and a pressure responsive member for controlling the operation o! said ,said .memberby said motor element.

of 'said lever and controlling `the operation of 8. Thefco'mbination in a uld pressure conand exhaust valves and a member iorcontrolling the operation of the valves, of means responsive to the pressure delivered by said valve for actuating said member inl vone direction, means responsive to a substantially constant pressure for actuating said member. in the opposite direction, an operating connection between said rst and second pressure responsive means, and means as sociated'therewith and movable relatively thereto for establishing a condition of balance between the forces exerted by said iirst and second named pressure responsive means when said first named pressure responsive means is subjected to a predetermined pressure.

9. The combination in a iluid pressure control valve having a casing provided with intake and exhaust valves and a pressure responsive member for controlling the operation of the valves, of a motor of a type exerting a SllbStl1-- troll valve having a casing provided with intake and exhaust valves and a pressure-responsive member for controlling the operation of the valves, of means for actuating said member including a motor for producing a' substantially constant force, an element connecting said motor and member and having a non-yielding connection therewith, and movable means cooperating with said element and ,casing and serving as a movable fulcrum for said element for controlling the force transmitted to said member through said element.

11. "Ihe combination in a fluid pressure control valve having a casing provided with intake and exhaust valves and va pressure-responsive member for controlling the operation of the valves, of a fluid motor of the type producing a substantially constant force for actuating said member, an element connecting said member and motor for transmitting force from the motor to the member and having a non-yielding pivotal said actuator for controlling the operation of said valvular means, a motor exerting a substantially constant force for controlling the operation of said valvular means, and means including a connecting element between said pressure-responsive means and motor and an operatar-controlled member cooperating with said element and movable with respect thereto for eiecting a balance of forces acting on said element regardless of the pressure acting on said first named pressure-responsive means.

ROGER H. cAsLER. i 

